1 package antlr;
2
3 * <b>SOFTWARE RIGHTS</b>
5 * <p>
6 * ANTLR 2.5.0 MageLang Institute, 1998
7 * <p>
8 * We reserve no legal rights to the ANTLR--it is fully in the
9 * public domain. An individual or company may do whatever
10 * they wish with source code distributed with ANTLR or the
11 * code generated by ANTLR, including the incorporation of
12 * ANTLR, or its output, into commerical software.
13 * <p>
14 * We encourage users to develop software with ANTLR. However,
15 * we do ask that credit is given to us for developing
16 * ANTLR. By "credit", we mean that if you use ANTLR or
17 * incorporate any source code into one of your programs
18 * (commercial product, research project, or otherwise) that
19 * you acknowledge this fact somewhere in the documentation,
20 * research report, etc... If you like ANTLR and have
21 * developed a nice tool with the output, please mention that
22 * you developed it using ANTLR. In addition, we ask that the
23 * headers remain intact in our source code. As long as these
24 * guidelines are kept, we expect to continue enhancing this
25 * system and expect to make other tools available as they are
26 * completed.
27 * <p>
28 * The ANTLR gang:
29 * @version ANTLR 2.5.0 MageLang Institute, 1998
30 * @author Terence Parr, <a href=http://www.MageLang.com>MageLang Institute</a>
31 * @author <br>John Lilley, <a href=http://www.Empathy.com>Empathy Software</a>
32 */
33
34 class TokenQueue {
35 private Token[] buffer;
37 private int sizeLessOne;
39 private int offset;
41 protected int nbrEntries;
43
44
45 public TokenQueue(int minSize) {
46 int size;
48 for (size = 2; size < minSize; size *= 2) {;}
49 init(size);
50 }
51 * @param tok The token to add
53 */
54 public final void append(Token tok)
55 {
56 if (nbrEntries == buffer.length)
57 {
58 expand();
59 }
60 buffer[(offset + nbrEntries) & sizeLessOne] = tok;
61 nbrEntries++;
62 }
63 * @param idx The index of the token to fetch, where zero is the token at the front of the queue
65 */
66 public final Token elementAt(int idx) {
67 return buffer[(offset + idx) & sizeLessOne];
68 }
69
70 private final void expand()
71 {
72 Token[] newBuffer = new Token[buffer.length * 2];
73 for (int i = 0; i < buffer.length; i++)
77 {
78 newBuffer[i] = elementAt(i);
79 }
80 buffer = newBuffer;
82 sizeLessOne = buffer.length - 1;
83 offset = 0;
84 }
85 * @param size The initial size of the queue
87 */
88 private final void init(int size) {
89 buffer = new Token[size];
91 sizeLessOne = size - 1;
93 offset = 0;
94 nbrEntries = 0;
95 }
96
97 public final void removeFirst() {
98 offset = (offset+1) & sizeLessOne;
99 nbrEntries--;
100 }
101 }
102